This invention relates to a method of checking the accuracy of the result of a multistep etching process for forming depressions in a substrate.
Components which have high-precision micropatterns are produced by etching. This involves providing them with etch masks using a photolithographic technique. If the micropatterns are complex, i.e., if they have different depths, and are additionally interleaved, two or more etching operations have to be performed.
Since the results of the different etching operations must be precisely positioned relative to each other, it is necessary to accurately align the different etch masks with one another, for which suitable apparatus is available. It is also necessary to be able to check the result of the multistep etching process for accuracy after completion of the micropattern.
The technical problem to be solved by the invention is to provide a means whereby it is possible to check in a simple manner whether the high-precision micropattern has the required accuracy after the multistep etching process.
According to the invention, a line pattern is provided on the etch masks, and the line patterns on the etch masks for different etching steps differ in such a way as to form a vernier system.
In applying this solution, a line pattern from which any deviation and its magnitude can be read directly is etched on the etched substrate.